This invention is directed to amorphous thermoplastic terpolymers containing sulfone groups.
Polyarylene polyethers are described in, for example, U.S. Pat. No. 4,175,175. This patent describes a polymer which has the following structure: ##STR5## This polymer is commercially available and is a tough, rigid, high strength thermoplastic which maintains its properties over a wide temperature range from -150.degree. F. to above 300.degree. F. Polymer (A) has a good combination of mechanical properties and exellent electrical properties. Said polymer is highly resistant to mineral acids, alkali and salt solutions but will be attacked by environments such as polar organic solvents. Thus, there is a need to improve the environmental resistance, particularly the environmental stress crack resistance of Polymer (A) so that it can be used in applications where it will be exposed to an aggressive solvent environment.
Attempts have been made to develop polymers which have the good properties of polymer (A) and additionally, improved environmental stress crack resistance.
The following polymer (B): ##STR6## has a good balance of mechanical properties, and possesses higher notched impact strength and heat deflection temperature than polymer (A). Additionally, polymer (B) has improved stress crack resistance. However, polymer (B) is prepared from 4,4'-dichlorodiphenyl sulfone and 4,4'-biphenol. The 4,4'-biphenol is difficult and costly to prepare and does not readily lend itself to commercialization.
Accordingly, a need still exists for a polymer which has the good combination of mechanical properties of polymer (A) and improved environmental stress crack resistance.
A novel class of amorphous thermoplastic terpolymers has been discovered which can be easily prepared are inexpensive and thus lend themselves to commercialization. They possess an excellent combination of mechanical properties. Additionally, these novel terpolymers display high notched izod impact values, high heat distortion temperatures and have excellent environmental stress crack resistance.